You can download the manual many of the HPI kits directly from HPI from their website (http://www.hpiracing.com/instructions/
). I would suggest downloading both the RS/4 Sport and Pro manuals.
The HPI Sport/Pro kits share many parts, but the steering racks are slightly different. Also the PRO kit came with many of the upgrade parts. Both kits can be configured to use a stick pack or saddle pack. I should also mention that those kits share many parts with older HPI nitro cars, so it shouldn't be too difficult to find replacement parts.
One other thing, the Sport/Pro can also be configured as a 190mm or 200mm car. You would use the same a-arms but different dog bones or CVDs - the part numbers will be in the manuals.
One last item, these cars where designed to run brushed motors - which are a small diameter. You may have issues of the rear belt rubbing on a brushless motor when installed. If your car didn't come with a rear belt tensioner, this can help with the belt rub in the rear. Brushless motors also use smaller spurs/larger pinions, which should help with that issue as well. The real issue on these cars is that you adjust the motor up/down for gear mesh.
Hope this info helps.